From the cooler, the wire and plug from that sensor should be accessible from the passenger's side front of the radiator. So that sounds like the correct one to me. Follow it back to the cooler and if it looks like the one that bolts into the passenger's side "tank" of the trans cooler from the bottom, you got it. And that's the one that people seem to say fail the most frequently.

And it's not "my" perspective of what left and right is on a vehicle. It _is_ the way it is, and if you don't know that you will be lost in service manuals. Driver's and passenger's side is typically not used unless you can be 100% positive whether it is a RH or LH drive vehicle, and since Discos were available either way you can see the need to standardize the perspective used for directions. It's just an auto industry thing.